1. Field of the Invention
The present invention relates to image transmission systems. More specifically, the present invention relates to image transmission over optical waveguides.
While the present invention is described herein with reference to illustrative embodiments for particular applications, it should be understood that the invention is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications, and embodiments within the scope thereof and additional fields in which the present invention would be of significant utility.
2. Description of the Related Art
Image transmissions systems either transmit an optical image or an electrical representation of the optical image. Electrical image transmission systems are often limited by bandwidth constraints. Accordingly, optical image transmission is often preferred over electrical image transmission where large amounts of image data are required.
Optical image transmission systems use either multiple optical fibers or a single optical fiber. In multiple fiber systems, the image is input to an array of fibers. Each fiber conveys the average image intensity of an associated pixel. With one fiber being provided for each pixel of output image data required, an image of 1,000 by 1,000 pixels requires a fiber optic bundle of 1 million fibers. Additional fibers may be required for redundancy in the event of breakage and/or defective fibers. As these multiple fiber bundles are expensive and bulky, single fiber image transmission systems have been investigated with limited success.
Single fiber systems include digital and analog image transmission systems. In digital systems, the image is digitized and transmitted as a series of optical pulses along the optical fiber. Conventional digital optical image systems suffer from the cost associated with the analog to digital and digital to analog conversion apparatus required and low transmission rate due to the bandwidth limitations imposed by the dispersion characteristics of the fiber.
Analog optical image transmission involves the transmission of the image down the optical fiber without conversion to the digital domain. Unfortunately, the different propagation velocities of different modes down a multimode fiber results in a scrambling of an image sent down the waveguide. Hence, previous attempts to transmit an image down a single fiber have required the use of carefully controlled gradient index fibers which behave like a series of periscope lenses continually focusing and defocusing the image down the fiber. Unfortunately, gradient index fibers are generally difficult and expensive to manufacture. In addition, the resolution of gradient index fibers is limited.
Thus, there is an ongoing need in the art for an inexpensive technique for transmitting an image along an optical waveguide.